I find this thread interesting because folks on both sides of the spectrum have interesting comments. At the end of the day, we should be happy that BMW sells the car here in the first place as more than 50% of the countries in the world, you can't even get one unless one pays more than double, triple the amount paid in US or Canada. I think I will take the fact that I am living in a country if not with the lowest price but definitely second or third lowest. For example, a used E90 M3 excluding govt. charges is listed for $160,000 ($170,000 CAD). You can imagine what the new pricing would be.
On the other hand, if you find a used M3 in the U.S. with specs. you are looking for then go for it. I can vouch for the fact that custom and overall import process is easy as I moved to Canada from U.S. last year and imported two cars and didn't have an problem selling my E46.
it is a win-win for everyone, just depends what you're looking for...